rtc: imxdi: monitor a security violation at runtime

Maybe the unit enters the hardware related state at runtime and not at
system boot time (after a power cycle).

Signed-off-by: Juergen Borleis <jbe@pengutronix.de>
Signed-off-by: Robert Schwebel <rsc@pengutronix.de>
[rsc: got NDA clearance from Freescale]
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

1 files changed, 19 insertions, 2 deletions

diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c
index 3d7f0390170e..a08da4a353db 100644
--- a/drivers/rtc/rtc-imxdi.c
+++ b/drivers/rtc/rtc-imxdi.c
@@ -665,6 +665,25 @@ static irqreturn_t dryice_norm_irq(int irq, void *dev_id)
         irqreturn_t rc = IRQ_NONE;
 
         dier = readl(imxdi->ioaddr + DIER);
+        dsr = readl(imxdi->ioaddr + DSR);
+
+        /* handle the security violation event */
+        if (dier & DIER_SVIE) {
+                if (dsr & DSR_SVF) {
+                        /*
+                         * Disable the interrupt when this kind of event has
+                         * happened.
+                         * There cannot be more than one event of this type,
+                         * because it needs a complex state change
+                         * including a main power cycle to get again out of
+                         * this state.
+                         */
+                        di_int_disable(imxdi, DIER_SVIE);
+                        /* report the violation */
+                        di_report_tamper_info(imxdi, dsr);
+                        rc = IRQ_HANDLED;
+                }
+        }
 
         /* handle write complete and write error cases */
         if (dier & DIER_WCIE) {
@@ -675,7 +694,6 @@ static irqreturn_t dryice_norm_irq(int irq, void *dev_id)
                         return rc;
 
                 /* DSR_WCF clears itself on DSR read */
-                dsr = readl(imxdi->ioaddr + DSR);
                 if (dsr & (DSR_WCF | DSR_WEF)) {
                         /* mask the interrupt */
                         di_int_disable(imxdi, DIER_WCIE);
@@ -691,7 +709,6 @@ static irqreturn_t dryice_norm_irq(int irq, void *dev_id)
         /* handle the alarm case */
         if (dier & DIER_CAIE) {
                 /* DSR_WCF clears itself on DSR read */
-                dsr = readl(imxdi->ioaddr + DSR);
                 if (dsr & DSR_CAF) {
                         /* mask the interrupt */
                         di_int_disable(imxdi, DIER_CAIE);